One day our neighbor, Annette Tunis, came by to visit. When she was in the Scale House, she said, "You know, you should add a fireplace over in that corner." She was right. We bought one, and carefully followed the installation directions (we hired a pro to put in the gas lines, however). Many people have enjoyed it since...thank you, Annette! :-)
The interior was dark because there were no windows, but letting in the light only made it easier to see how rotten some of important beams were. To fix the damage in the photo above, we had to remove the exterior planks, then jack up the west wall of the building and replace the horizontal "sill" beam, plus splice in a new section of the main vertical beam that rested on it. The floor boards in that area were also rotten beyond repair on that end. Fortunately, that is exactly where the new stairs went to create access to the new loft, so now the staircase covers the replacement boards we had to use.
In order to put in the windows, the middle horizontal beam around the exterior of the barn, used to nail on the wood plank siding, had to be lowered several inches. That meant we first had to remove, one side at a time, all the exterior planks and batten strips, then move the beam down, and then put in the window casings, and then re-plank the barn around the new windows. We added studs for drywall or new (salvaged) wood planks to create the inside walls. Some drywall made the interior brighter, but the planks preserved the "look" of the interior, and of course, we made sure all of the original beams still showed on the inside.
Finally, we hired an electrician to install a new main electric panel, but we ran all the circuits in the building for lights and outlets. Once the wiring was complete, it was time to have the interior walls insulated with spray-in "wet" cellulose (see photo below).
The last step was to cover the walls with planks & drywall, and trim around the windows and doors. We also took up all the wooden floor boards, power washed them, insulated below them, and put them back.